Can anyone tell me what capacitor checker would be good to get. I have looked at esr cap testers but not sure if I really need an esr. I wan to check the caps in an old tube radio so I can easily unhook the caps from the circuit so I am not sure if I need esr tester. Anyone have any thoughts on it? Thanks, Warren

I would worry about leakage more than anything, I think. Old tube radios may have worn out, dried up filter caps, but in many of them, the coupling caps are going to be leaky. For example, almost any of those wax coated caps is going to be crummy. I usually test for that mainly by checking for leakage in the circuit. If I have 180v on one side of the cap and OUGHT to have 0v DC on the other end, but find say 15v, then I know the cap is leaking.

A tester for that MUST have a high voltage mode. Caps that test just fine at a volt or two - as in any hand meter - can leak like a sieve at higher voltages. I see plenty of caps that should handle 450v, but leak at anything over 200v.

The old Heathkit and Eico cap testers with the "magic eye" tube on the front were actually pretty good at this.

I have one that I built into a small plastic case as a general purpose component tester. The measurements of ESR are not as accurate as a dedicated ESR meter but for the price it is a worthwhile addition to the tool-kit. It is useful to give an indication of the value of capacitors which can be removed from circuit as it is not suitable for in circuit measurements. It's always advisable to make sure any capacitors are fully discharged before measuring as there is no protection built in. Always check with an ohm-meter on any old capacitors as they are prone to go leaky. As a bonus it can be used to identify the connections of transistors, FETs and diodes as well as measuring Rs, Ls and Cs.